Production of lactams

ABSTRACT

LACTAMS ARE PRODUCED BY HEATING A COMPOUND OF FORMULA,   3,3-(-X-),5,5-(-X&#39;&#39;-)-1,2,4-DIOXAZOLIDINE   WHERE X AND X&#39;&#39; ARE DIVALENT ALIPHATIC RADICALS WHICH MAY BE THE SAME OR DIFFERENT, IN SOLUTION IN A NON-HYDROCARBON ORGANIC SOLVENT CONTAINING A SALT OF AN ELEMENT OF GROUP I OR II.

United States Patent 3,583,982 PRODUCTION OF LACTAMS Clifford William Capp, Ewell, Keith Warwick Denbigh, Epsom, Peter John Durston, Thames Ditton, and Brian Walton Harris, Horley, England, assignors to BP Chemicals UK. Limited, London, England No Drawing. Filed May 22, 1968, Ser. No. 731,291 Claims priority, application Gleat Britain, June 6, 1967,

Int. Cl. C07d 41/00, 11/06, 53/00, 87/54, 93/36 US. Cl. 260-239.3 48 Claims ABSTRACT OF THE DISCLOSURE Lactams are produced by heating a compound of formula,

where X and X are divalent aliphatic radicals which may be the same or different, in solution in a non-hydrocarbon organic solvent containing a salt of an element of Group I or H.

The present invention relates to a process for the production of lactams.

According to the present invention the process for the production of lactams comprises heating a solution of a compound of formula,

A NH

\/ \J v (I) Where X and X are divalent aliphatic radicals which may be the same or different, in anon-hydrocarbon organic solvent containing a salt of an element of Group I or II.

Compounds of Formula I, hereinafter referred to as peroxyamines I), and processes for their production are described in Belgian Pat. 701,327.

In each of radicals X and X the number of carbon atoms which form part of each of the rings shown in the Formula I may for example vary from 4 to 11, ie the total number of carbon atoms which form part of each of the ringsmay be between 5 and 12: Examples of compounds of Formula I which may be used are those compounds where X and X are radicals each having 4 to 6 carbon atoms in the ring. Examples of such compounds are (a) R R R R R NH R R 00 R R R R B R R R and (b) R R R R 50 i .of magnesium, as well as the alkaline earth metals, e.g.

3,583,982 Patented June 8, 1971 where each of the radicals R is alkyl or hydrogen. All the substituents in a ring need not be identical. For example one of the groups R may be methyl while the others are hydrogen.

The preferred compounds are those in which each of the radicals R is hydrogen or lower alkyl, e.g. having 1 to 5 carbon atoms such as methyl, ethyl, and propyl.

Specific examples of compounds which may be used are 1,1-peroxydicyclopentylamine, 4,4'-dimethyl-1,l-peroxydicyclohexylamine, 1,l'-peroxydicyclohexylamine and 1,1'-peroxydicycloheptylamine.

The reaction is carried out in the presence of a solvent so that the reaction mixture will contain a component in addition to the reactants and the reaction products. The solvent may be a solvent of high di-electric constant preferably one having a di-electric constant greater than 20, for example one having a di-electric constant greater than 25 (measured at 20 C.). The solvent may for example be a non-aromatic solvent. Examples of such solvents are the aliphatic hydroxy compounds, eg, diand poly-hydroxy compounds such as ethylene glycol, diethylene glycol and butane-1, 4-diol; substituted or unsubstituted alkanols such as methanol, ethanol, ethoxyethanol and tetrahydrofuryl alcohols. Examples of other solvents which may be used are the ketones, e.g. dialkyl ketones such as methyl ethyl ketone, methyl isobutyl ketone, and alkyl aryl ketones; e.g. acetophenone. Aldehydes may be used, e.g. n-hexaldehyde and also amides such as dimethyl formamide. Specific examples of other solvents which may be used are dimethyl sulphoxide, tetrahydrothiophen-l,l-dioxide, nitromethane, pyridine and dibutyl phthalate. Either a single solvent or a mixture of solvents may be used.

.Chemistryiby. Cotton and..Wilkinson (1962). Examples of elements of Group -I-A whose salts may be used are lithium, sodium and potassium. Examples of the salts of the elements of Group II-A which may be used are salts calcium, barium, and strontium. These salts may be for example halides or thiocyanates.

-Any given salt will generally give the best results when used in conjunction with a specific solvent or class of solvents. Among specific combinations of solvents and salts which are particularly satisfactory are dimethyl sulphoxide with lithium chloride, lithium bromide, lithium iodide, calcium chloride, magnesium chloride, potassium thiocyanate, the best salts being lithium chloride and bromide, calcium chloride, magnesium chloride and potassium thiocyanate; acetone and lithium bromide; methanol and lithium chloride, sodium chloride, calcium chloride, strontium chloride and strontium bromide, of which the best are lithium chloride and calcium, barium and strontium chloride and strontium bromide; ethanol and lithium bromide and chloride; ethylene glycol and potassium" fluoride; diethylene glycol and potassium bromide; didroxy compounds such as ethylene glycol, diethylen glybe possible toseparate the solvent, lactam, cyclic ketone and other products by distillation. Any residual salt may be recovered by extracting the residue left after distillation with a minimum amount of water, separating off the ketone and lithium bromide; methyl isobutyl ketone and aqueous layer and then evaporating off the Water to give lithium chloride; acetophenone and lithium bromide; the salt, which may be recycled to the reaction.

ethoxyethanol and lithium bromide; and tetrahydrofur- Alternatively the reaction mixture may be diluted With furyl alcohol and lithium bromide. Of these the best com water and then extracted with a liquid which is immiscible binations appear to be lithium bromide with methyl ethyl with Water and is a solvent for the lactam. Examples of ketone, methyl isobutyl ketone, acetone, acetophenone, suitable solvents are aromatic compounds e.g. benzene and methanol, ethanol or acetonitrile; and lithium chloride xylene, aliphatic hydrocarbons e.g. petroleum distillate and with ethanol, dimethylformamide, or dimethyl sulphoxchlorinated hydrocarbons, especially the chlorinated lower ide. v, aliphatic hydrocarbons e.g. methylene chloride, carbon The quantity of solvent used to prepare the solution of tetrachloride, chloroform, dichloroethane. Ethers may-also the peroxyamine (I) is preferably sufiicient to dissolve all be used. The lactam may be recovered from the extract the peroxyamine and salt fed to the reaction mixture. The by for example distilling oil the solvent used to extract it concentration of the peroxyamine in the solution may vary While the salt may be recovered from the aqueous layer, over a moderately wide range for example from 0.1 to 5.0 resulting from the addition of Water, by evaporating ofi moles/litre. The concentration of the salt in the solution the water. 5 I 5 may also vary over a moderately wide range for example The invention will now be illustrated by the following from 0.1 mole/litre to the saturation concentration which examples in which all the temperatures are in degrees will of course vary with the salt and solvent used. The Celsius. molar ratio of peroxyamine to the salt may vary widely. EXAMPLE 1 I i to Whlch the f' f A series of experiments was carried out in which'metal i t may 3 12 3 2 3 y Ia ge salts and 1,l'-peroxydicyclohexylamine were dissolved in example g an t u 1 2 3 various solvents and heated. The reaction product was fi f e 5 f a i ig diluted with water, extracted successively with chloroform i; 5 e 651ml 352 5 u 5. rilore and the chloroform extract analyzed. The quantities of t an or th e op salt, l,1'-peroxydicyclohexylamine and solvent, the reacg g i i b i so Ven an sa tion conditions, and the results obtained are given in Table use h e g} h F h t d d d 1. The solvents used were dimethyl sulphoxide (DMSO),

T f W 16 sofutlon epten methanol (MeOI-I) acetone, and methyl ethyl ketone upon t e 1 2 P s g i e .fi i fi (MEK). The products obtained were caprolactam (CL), of til; so utlon ust m at atc 5refiic 10h 1111 W ct y cyclohexanone (CH). The yields quoted in the table are Vary q g g h 11.1mm es 6 mac can expressed as moles of product per 100 moles of 1,1'-perf i out 3 5: muous g t oxydicyclohexylamine fed or charged to the reaction. The

e f Y ii g i peroxyamine conversion is the proportion of the l,l'-peri W1 coulse p 6 na ure 0 6 W0 oxydicyclohexylamine fed to the reaction converted to rings of which the radicals X, X for-m part. The number products 1 I of carbon atoms in the ring of the lactam molecule will 40 EXAMPLE 2 correspond to the number of carbon atoms 1n the ring of the peroxyamine from which it was formed. Where the Lithium bromide (5.14 g.) and 1,l-peroxydicyclohexylrings carry alkyl substituents alkyl substitutedlactams will amine (5 g.) in methyl ethyl ketone (25 ml.) were refluxed be formed. Thus 1,l'-peroxydicyclohexylamine which has for 2 hours. The reaction mixture was extracted with unsubstituted -6-membered rings gives caprolactam while chloroform and the extract analyzed as in Example 1. The 3,3'-dimethyl 1,1-peroxydicyclohexylamine prepared yields of caprolactam, cyclohexanone, and caproa-mide from 3-methylcyclohexanone by reaction with ammonia were 83.2%, 94% and 3.l% respectively. and hydrogen peroxide, and which has alkyl substituted 6- membered rings, gives a mixture of 3-methylcaprolactam 5O EXAMPLE -3 and S-methylcaprolactam.

The lactam can be recovered by any suitable method. In senes of expenments Wa$ arr1ed out as f p 1 some cases much of the salt crystallizes out on cooling the 115mg 5 f of '-P Y {Y y Wlth lithil ti t th nd f th r ti d i r t d by urn b rom1de as the salt and various solvents. The reaction filtration. Whether or not the salt crystallizes out it may c nditions and results are given in Table 2.

TABLE 1 Reaction conditions pelOXY- Peroxyamine Yield Weight dieyclohexyl- Vol. Temp. Time conversion Metal salt used (g.) amine (g.) Solvent (ml.) 0.) (hrs.) (percent) CL CH 5.0 40 110 2 100 84.6 91 5.0 40 10 95.4 86.9 94.3 4.2 40 110 2 87 68.0 86.0 7.2 40' 110 2 93 51.4 81 5.3 10. 40 110 2 61.8 36.7 2.0 10. 40 2 100 39.4 32.6 5.0 10. 40 110 2 100 74.4 80.0 10.0 10. 40 02 0.5 100 78.9 03.8 2.8 10. 40 110 2 03.1 58.4 73. 0 5.3 10. 40 110 2 86.2 75. 7 56.3 2 10, 40 110 2 100 89.8 98.1 2 10, 40 110 2 100 43.6 60 9.7 5. 25 130 1 100 62.1 100.5 11.8 5. 25 140 1 100 46 90.7 7.9 5. 25 I 1 100 40.5 93.4 5.15 5. 20 2 100 44.3 70.0 50 100 104 1.5 100 81.7 08.3 50 100 104110 1.7 00.5 85.4 00.5 24.4 100 105-108 3.0 100 78.3 85.0 3 50 120 1.3 100 48.2 89.0 10 40 110 2% 90 78.7 103 5 40 110 2% 100 60 88 1 TABLE 1Gonti11ued Reaction conditions 1,1'-peroxyv Peroxyamine Yield Weight dicyelohexyl- Vol. Temp. Time conversion Metal salt used 1 (g.) amine (g.) Solvent (mL) 0.) (hrs) (percent) CL CH 5 40 110 2 100 67 91.5 5.9 40 110 2% 100 72 91.5 2.0 40 110 2 s 77 6 96.4 2.0 40 110 2 100 69 92.4 5.0 40 110 3 98 66.0 90.3 10.0 40 110 2 95 50.0 5.0 40 110 2.5 91 40.0 96 5.0 30 so 30 98 43.0 66

1 10.7 g. sodium E.D.T.A. p 1 10.7 g. sodium E.D.'I.A. p

TABLE 2 p I 4. The process according to claim 1 wherein the compound has the formula, I Yield (percent Weight mole) R R R R s 1 251111 i 0%"; if; on 01. I R NH V R 0 Van grm. IS.

' 1 R- 0 o- R Methyl ethyl ketone 5.1 70-80 2 101 s5 Dimethyl sulphoxide. 5.1 130 2 89.4 67.8 Cyclohexanone 1 5.1 100 2 50.0 R RR R Acetophenone 4.35 130 2 80.7 80.0 R I RR R Methyl isobutyl ketone.- 4. 35 130 2 78. 6 81. 8 n-Amyl methyl ketone 8.70 1 130 2 90.0 74.0 R R R R Acetylaeetone. 4. 35 139 2 74. 2 73. 6 i'gfafigff iif {-33 a 'g' $1 2 wherein each of R is lower alkyl of 1 to 5 carbon atoms Nitromethane 1.30 161 2 33.4 3 .0 01 hydrogen. ggl figgfggggf gggg 2 1?, 3 3,1 3 3 5. The process according to claim 1 wherein the com- Butane-1,4-diol 5. 10 130 0. 7 72. 0 62. 0 pound has the formula, Dibutyl phthalate.. 5. 10 130 0. 7 50. 0 64. 0 Terpineol 5.10 130 1 57.0 R R R R Geraniol 5.10 130 1 52.0 R NH R R 00 R We claim: 1. The process for the production of lactams which R RR -R comprises heating a solution of a compound of the R? RRRR I RR 0 ul f rm a R R R R R R R R NH R wherein each of R 15 lower alkyl of l to 5 carbon atoms or hydrogen. R 40 6. The process according to claim 4 wherein the compound is 1,1'-peroxydicyclohexylamine. R 7. The process according to claim 1 wherein the sol- R vent has a high dielectric constant. R 8. The process according to claim 7 wherein the solvent has a dielectric constant greater than 20. R 9. The process according to claim 8 wherein the sol- R vent has a dielectric constant greater than 25. R 10. The process according to claim 7 wherein the solvent is a non-aromatic solvent. 11. The process according to claim 1 wherein the solvent is an aliphatic hydroxy compound. R NH R 12. The process according to claim 11 wherein the 501- R 00 R vent is a dior poly-hydroxy compound.

13. The process according to claim 12 wherein the R \RR- R solvent is ethylene glycol, diethylene glycol or butane-1,4- R I R diol.

1/ 14. The process according to claim 11 wherein the R R solvent is a substituted or unsubstituted alkanol. whfiein R is hydrogen or lower alkyl of 1 to 5 carbon 15. The process according to claim 14 wherein the atoms, in a non-hydrocarbon organic solvent containing alkalol methanol, fl or ethowethanola. salt selected from the group consisting of lithium, so- 1 T 6 Process accordmg to 0134111 10 Wherem the di 0t esium, calcium barium and strom solvent is tetrahydrofurfuryl alcohol. l t i g z gi g giig 17. The process according to claim 1 wherein the sol- 2. The process according to claim 1 wherein R is hyvent aka/tone 18. The process according to claim 17 wherein the drogen, methyl, ethyl or propyl.

3. The process according to claim 1 wherein the comketone adlalkyl ketone' 19. The process according to claim 18 wherein the pound has the formula ketone is methyl ethyl ketone.

R R R R 20. The process according to claim 18 wherein the ketone is methyl isobutyl ketone. 21. The process according to claim 17 wherein the :ketone is an alkyl aryl ketone.

22. The process according to claim 21 wherein the alkyl aryl ketone is acetophenone. wherein each of R is lower alkyl of 1 to 5 carbon atoms 23. The process according to claim 1 wherein the solor hydrogen. vent is an amide.

24. The process according to claim amide is dimethylformamide.

25. The process according to claim 9 wherein the solvent is dimethyl sulphoxide.

26. The process according to claim 7 wherein the solvent is tetrahydrothiophen-1,1-dioxide.

27. The process according to claim 9 wherein the solvent is nitromethane.

28. The process according to claim 1 wherein the solvent is pyridine.

29. The process according to claim 6 wherein the solvent is dibutyl phthalate.

30. The process according to claim 1 wherein a single solvent is used.

31. The process according to claim 1 wherein the salt is a lithium salt.

32. The process according to claim 1 wherein the salt is a sodium salt. I

33. The process according to claim 1 wherein the salt is a potassium salt.

34. The process according to claim 1 wherein the salt is a magnesium salt.

35. The process according to claim 1 wherein the salt is a calcium, barium, or strontium salt.

36. The process according to claim 1 wherein the salt is a halide.

37. The process according to claim 1 wherein the salt is a thiocyanate.

38. The process according to claim 1 wherein the quantity of solvent is sufiicient to dissolve all the peroxyamine and salt fed to the reaction mixture.

39. The process according to claim 1 wherein the concentration of the peroxyamine in the solution is at least 0.1 mole/ litre.

23 wherein the 40. The process according to claim 39 wherein the conlitre;

42. The process according to claim 1 wherein the solution'is heated to a temperature in the range to 161 C.

43. The process according to claim 42 wherein the solution is heated to a temperature of at least C.

44. The process according to claim 43 wherein the solution is heated to a temperature'of not more than 120 C.

45. The process according to claim 44 wherein the solution is heated to a temperature of not more than C.

46. The process according to claim 1 wherein the solution is heated for a time in the range 5 minutes to 5 hours.

47. The process according to claim 1 wherein thelactam' is recovered by distillation.

48. The process according to claim- :1 wherein the lactam is recovered by solvent extraction of thereaction product.

References Cited Roberts et al.: Basic Principles of Organic Chemistry, pp. 384-386 (1964) (Benjamin). 1

Derwents:- Belgian Patents Report, abstracting Belgian Patent 704,214, granted Sept. 22, 1967. 1

HENRY R. IILES, Primary Examiner R. T. BOND, Assistant Examiner US. 01. X.R. 260 -29 41, 404.5 

